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For the first time, researchers have managed to tag this furious shark
"The experience was both frightening and exciting," a researcher at the Institute of Marine Research said about the special encounter with a porbeagle shark.
While marine scientist and tagging expert Keno Ferter was at a meeting to discuss how to best tag porbeagles, several boats that take tourists fishing in Lofoten reported that they frequently catch the shark.
“We jumped on the next plane to Lofoten,” says Ferter.
About the porbeagle
Latin name: Lamna nasus
Other names: Mackerel shark, blue dog
Family: White sharks (Lamnidae)
Maximum size: 3 metres long and 150-200 kg
Range: The North Atlantic and Mediterranean at depths of 200–700 metres
Diet: Mackerel and herring
Characteristics: Conical snout and torpedo-shaped body
The porbeagle is a fast swimmer and is in the same family as the feared great white shark. Found along most of the Norwegian coast and in other northern seas, it can reach over 3 metres in length and weigh more than 200 kg. This means it is around half as big as the great white shark, yet this is still an impressive size when you want to tag this individual from a small angling boat.
Ferter and his colleagues have lots of experience of tagging various species of ‘marine megafauna.’ He himself has tagged everything from saithe to bluefin tuna weighing hundreds of kilos, and helped to tag a mackerel shark in Australia as well as basking shark in Norway earlier this summer.
Ferter was nevertheless not prepared for what happened when it was the porbeagle’s turn.
“Incredibly powerful forces come into play. I’ve never experienced anything so strong, and we have tagged bluefin tuna that weigh hundreds of kilos. The experience was both frightening and exciting. The porbeagle has many sharp teeth, and you have to treat them with respect,” says Ferter.
In order to tag a porbeagle, you first have to get it to bite, and then you have to manage to haul it in. That requires strong fishing rods, a strong fishing line, wire and a whole fish as bait. Thanks to invaluable help from experienced fishing guides at Nordic Sea Angling in Lofoten, after two days the researchers managed to catch a porbeagle and get it close to the boat.
But the hardest part of the job was still to come. How do you get an untamed shark weighing over 100 kilos to stay still long enough for you to attach the tag to its dorsal fin?
“Well, it is not easy! In order to keep the shark still we put a rope around its body, just in front of the dorsal fin, so that it lay up against the boat while we worked. The porbeagle we caught was around 2.5 metres long and weighed at least 100 kilos,” Ferter says. “It put up a good fight, and it took some time for us to succeed by trial and error. Luckily, we got there in the end, and we are really happy to have demonstrated that it is possible to tag a porbeagle. We also lost another shark from the hook in the final step of the race, but we have learned a lot for the next time we do this."
Each species of fish behaves in a completely different way, which means that the researchers have to adapt their strategy.
“Bluefin tuna, for example, stay completely still provided we manage to get their head above water. The porbeagle, on the other hand, completely loses it if you do that,” Ferter explains.
Sharks on the Move
The satellite tagging of a porbeagle and basking shark off Lofoten is part of the Sharks on the Move project, which looks at migratory sharks like the porbeagle, basking shark and spurdog. The aim is to learn more about the current and future distribution of these three species in Norwegian waters, using methods including tagging experiments and data modelling.
“The Porbeagle is known for being highly mobile and capable of travelling thousands of kilometres across the whole Atlantic, but unfortunately we know too little about where they spend their time in Norwegian waters and how they migrate,” says shark researcher and project manager Claudia Junge.
In half a year the satellite tag will pop up and send data from the first tagged porbeagle to the researchers.
They are aiming to tag at least 10 porbeagles and 5 basking sharks by the end of 2023. Some of those tags will enable them to follow their migration in real-time.
How the satellite tags work
- The satellite tags used here work like a data logger, recording information about light, pressure, time and temperature in their internal archive.
- They release themselves after a programmed amount of time and transmit their data to the researchers via a satellite system.
- A complex calculation then allows the scientists to reconstruct the movement tracks of the porbeagle.
- The tag that was attached to this porbeagle was financed by ICCAT, the International Commission for the Conservation of Atlantic Tunas, and it will be released 180 days after deployment.
The researchers would like your help
If you see a porbeagle, basking shark or anything else unusual in the ocean or along the coast, please report your observation to the portal Marine Citizen Science (“Dugnad for Havet”)!
This will enable more knowledge about ecosystems and the marine environment to be collected. And perhaps some researchers are ready to jump on a plane in response?
About the project ‘Sharks on the Move’
"Sharks on the Move: species distribution modelling of migratory sharks to inform ecosystem-based management under global change" is financed by the Research Council of Norway.
The project is led by the IMR and involves 20 experts from seven scientific partner institutions in Norway and overseas, as well as the Directorate of Fisheries and Runde Miljøsenter AS. The participating research institutions are the IMR, NIVA, NORCE, University of Oslo, UiT The Arctic University of Norway, CIBIO/University of Porto (Portugal) and University of Miami (US).
The project’s advisory board is made up of renowned British and French experts on the movement ecology of sharks, as well as representatives of the Norwegian Environment Agency and Norwegian Biodiversity Information Centre.
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